Salt Thickened liquid soap separating at low temps

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saffy

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Not been on this forum for a while so apologies if this has been covered elsewhere.

I have a working liquid soap recipe as in can reliably saponify to get the paste and then dissolve to get the liquid. Have been thickening with 25% w/w NaCl which is fine until it gets cold - when the thickened soap separates into ’lipid’ and aqueous phases. Can be warmed and remixed - but is not a good selling point. Any ideas on how to stabilise this? Another thickener?
 

ResolvableOwl

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Salt as a thickener definitely has its rough edges, and some LSers have given up on it for good reasons. In your case, difficult to tell with no further background. Which oils do you use? Some oils react more well-behaved towards salt than others. IIRC saturated FAs (like from lard, butters, RBO) are the more troublesome ones, that don't contribute that much to viscosity, but love to separate.

What is your opinion of resorting to wonder emulsion stabilisers like polysorbate-80 or alkyl glucosides?

 

Zany_in_CO

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As a general rule of thumb,
LS with 100 % olive oil (and similar) can be thickened with table salt brine.
LS with over 20% coconut oil (and similar) can not.

As @ResolvableOwl mentioned, it would helpful if you could provide your formula, including water-to-KOH ratio and superfat. Also, your process (HP? CP? ETC.) including dilution phase.

NOTE of CLARIFICATION: Technically, Polysorbates (20, 80, 60) are "solvents" used to make oils, fats, butters, etc. water-soluble.

TIP on THICKENING: Having tried almost every "thickener" available at the time, and not happy with the result, I rely on dilution rates to find the perfect measure of soap-to-water as discussed in this thread.
 

ResolvableOwl

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@Zany_in_CO Slightly tangential, but I'm really impressed how you constantly manage to keep track of all the topical relevant places all over SMF and the whole interwebz. 😍
 

saffy

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Salt as a thickener definitely has its rough edges, and some LSers have given up on it for good reasons. In your case, difficult to tell with no further background. Which oils do you use? Some oils react more well-behaved towards salt than others. IIRC saturated FAs (like from lard, butters, RBO) are the more troublesome ones, that don't contribute that much to viscosity, but love to separate.

What is your opinion of resorting to wonder emulsion stabilisers like polysorbate-80 or alkyl glucosides?

using 33% coconut + 57% light olive (chemical extraction I think) + 10% castor

Had a quick look at PS but could not get to dissolve and should try more approaches. Looked at Na-Alginate and not too successful plus concerns over consistency of sources in terms molecular structures involved according to my reading.

Lacking in time to systematically test a few - will check out the alkyl glycosides.
 

ResolvableOwl

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Lacking in time to systematically test a few - will check out the alkyl glycosides.
Me neither :(. I've had limited success with “rescuing” LS that had went grainy with CMC, by adding caprylyl/capryl polyglucoside. Just to learn afterwards that CMC seems to not like salt solutions (like soaps are).
 

RDW

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in industry we never thickened beyond 5%wt salt, ideally we didn’t want to go over 3%wt for clarity. You could try shifting the salt curve by adjusting pH. As others have also said, non-ionic alkyl polyglucosides would also work. You could also try rheology modifiers like Xanthan gum or Tego remo.
 

Zany_in_CO

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33% coconut + 57% light olive (chemical extraction I think) + 10% castor
Assuming you use Water:KOH ration of 3:1 and 0% SF, you end up with a SAT/UNSAT ratio of 38/62.

NOTE: Thickening with salt brine doesn't work well with coconut oil over 20%, if at all.
I would raise the coconut to 50%, lower the olive to 45% and castor to 5%.
Then, for the best viscosity, dilute with 40% soap to 60% water. (No thickening needed)

As it is, I have no problem with using "light olive" as long as long as it isn't adulterated. (?) Your formula makes a lovely LS with good Values for Lather, Cleansing, and Conditioning!

Dilution is key: To find the "perfect measure" of soap-to-dilution water ratio, make up a batch of 12 oz. oils which results in 16 oz. (approx.) paste that you can then divide into four 4 oz. portions to play with.
40%, 35%, 30%, & 25% paste to water.

Keep in mind that in addition to an acceptable viscosity, you also want the LS to rinse off quickly with no residue. 40% soap may take longer to rinse off cleanly and a lot of soap is wasted; 25% may be too watery.

Hopefully, you'll find the happy medium, i. e., no thickening required -- just like the "Pros". ;)

HTH

saffy's LS.png
 
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Professor Bernardo

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I would raise the coconut to 50%, lower the olive to 45% and castor to 5%.
Then, for the best viscosity, dilute with 40% soap to 60% water. (No thickening needed)
What @Zany_in_CO said!

Much simpler to follow this route than try and figure out NaCl ratios. I figured this out the hard way over 20 years ago when I was first learning liquid soap.
 

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